My Check Engine light can't be reset and stays on constantly. I don't know the code but was told it is a rare code and indicates a bad CPU/ramset and the computer needs replaced. Has anybody had this happened and is it something I can do myself? I have fairly good mechanical skills, replacing parts etc., but never have torn apart and rebuilt anything.

Yep, I found the ECM above the battery, took the plastic cover off, and after taking a bunch of notes, I got a used rebuilt one ordered. OEM for new was $600 and the parts man said there was only ONE available in the whole country.

No. If this is an actual cpu rom failure, you will need a new ecu. These ECUs are encased in resin. Is is p0605?

My 2004 is doing the same thing. P0605 code on the reader. There is a list on this forum that indicates the TCM. I ordered a new one from the dealer today. I got the ROM message on the scanner. I'm hoping this is the problem. The scanner said "internal module error No ROM"
Hope this works and helps everyone.